13° 



THE POPULAR SCIENCE MONTHLY 



light. These discourses, which constitute 

 the present volume, were delivered in No- 

 vember, 1883. In the first, the emission 

 and the undulation theories of light are 

 stated, and the insufficiency of the former 

 is shown. Explanations of the phenomena 

 of interference and diffraction by means of 

 the undulation theory follow, and, in the 

 third and fourth lectures, double refraction, 

 polarization, and the interference of polar- 

 ized light are considered. 



Chemistry : General, Medical, and Phar- 

 maceutical, including the Chemistry of 

 the United States Pharmacopoeia. By 

 John Attfield, F. R. S. Tenth edition, 

 specially revised by the author for Amer- 

 ica. Philadelphia : Henry C. Lea's Son 

 & Co. Pp. 727. 



This compact volume is, first of all, a 

 text-book of general chemistry, in which 

 the substances and processes used in medi- 

 cal and pharmaceutical chemistry have been 

 employed in illustrating the principles of 

 the science. " From other chemical text- 

 books," says the author in his preface, "it 

 differs in three pai-ticulars : first, in the 

 exclusion of matter relating to compounds, 

 which at present are only of interest to the 

 scientific chemist ; secondly, in containing 

 more or less of the chemistry of every sub- 

 stance recognized officially or in general 

 practice as a remedial agent ; thirdly, in the 

 paragraphs being so cast that the volume 

 may be used as a guide in studying the sci- 

 ence experimentally." The book contains 

 also directions and tables for qualitative 

 and quantitative analyses, and in these de- 

 partments, lilcewise, special prominence is 

 given to substances used as drugs. Natu- 

 rally, organic compounds receive more at- 

 tention than in the ordinary text-book on 

 general chemistry, and a large amount of 

 information, valuable to the physician and 

 the pharmacist, is distributed through the 

 volume. 



Electricity, Magnetism, and Electric Te- 

 legraphy. By Thomas D. Lockwood. 

 New York: D. Van Nostrand. Pp. 377. 

 Price, $2.50. 



Telegraph and telephone operators, 

 line-men, and others connected in similar 

 capacities with the applications of elec- 

 tricity, have generally had scanty oppor- 

 tunities for education, and seldom possess 



a sufficient understanding of electrical sci- 

 ence to enable them to attain important 

 and lucrative positions. It is especially for 

 this class that the present book is written, 

 though it is equally available for the gen- 

 eral reader who wishes to understand the 

 construction and operation of the electri- 

 cal apphances which he sees in use. The 

 text is arranged in the form of question 

 and answer, the answers varying from 

 a few lines to a couple of pages in 

 length, and is illustrated with 152 cuts. 

 Frictional and voltaic electricity, thermo- 

 electricity, and magnetism, are taken up in 

 successive chapters, questions about dyna- 

 mo-electric machines are then answered, 

 and two chapters are devoted to methods 

 of electrical measurements, and to the 

 terms and units used. The next eigbt 

 chapters are devoted to telegraphy, begin- 

 ning with the principles as exemplified in 

 different systems, and including such sub- 

 jects as line-construction and the adjust- 

 ment and care of telegraph - instruments. 

 Electric lighting, electro - metallurgy, elec- 

 tric bells, electro-therapeutics, and the tele- 

 phone, are dealt with in single chapters, 

 and a number of minor applications receive 

 brief mention. Tables showing the weight 

 and electrical resistance of various qualities 

 of wire and other tables are appended. 



The Principles of Ventilation and Heat- 

 ing, AND their Practical Application. 

 By John S. Billings, M. D., LL. D., 

 Surgeon U. S. Army, New York: "The 

 Sanitary Engineer." Pp. 214. Price, $3. 



This book contains the substance of a 

 series of articles originally published in 

 " The Sanitary Engineer," with some new 

 matter. It is intended to present the gen- 

 eral principles which should guide a person 

 in judging of various systems of, and ap- 

 pliances for, ventilation. Dr. Billings in- 

 sists on the inseparable connection between 

 ventilation and heating, and lays down as 

 his first axiom, which applies especially to 

 the large cities in our Northern States, that 

 " in this climate it is impossible to have at 

 the same time good ventilation, sufficient 

 heating, and cheapness." After some pre- 

 liminary considerations of heat and gases, 

 the author takes up methods of heating, 

 patent systems of ventilation and heating, 

 means for removing dust and for supply- 



